Do painkillers interfere with antidepressants?

NEW YORK (Reuters Health) - Certain types of antidepressants may not work as well in people that take painkillers such as ibuprofen and aspirin, suggests a new study.

The findings can't prove that the painkillers, called non-steroidal anti-inflammatory drugs, or NSAIDs, stop antidepressants from working, the authors said. But the possible link is something for patients with depression - and the doctors treating them - to think about when treating pain and inflammation, researchers report in Proceedings of the National Academy of Sciences, or PNAS.

"This is certainly something that clinicians and individuals should be keeping in mind," Jennifer Warner-Schmidt, the study's lead author from The Rockefeller University in New York City, told Reuters Health.

"If you're taking an SSRI antidepressant and it's not working so well for you, one possibility could be that the anti-inflammatory drugs are having an effect there," she said.

By analyzing the brains and behavior of mice treated with Celexa, a drug from the class of antidepressants called selective serotonin reuptake inhibitors, or SSRIs, Warner-Schmidt and her colleagues found that mice treated with Celexa and an NSAID had lower levels of the antidepressant in their blood than those that were only given Celexa.

Mice that were given a painkiller and antidepressant also did worse on tests measuring their stress and depression than those who just took the antidepressant.

The effect wasn't limited to rodents. The same researchers analyzed data from a previous study done on about 1,500 people treated with Celexa for 12 weeks. Those participants also reported if they took an anti-inflammatory drug such as aspirin or ibuprofen during antidepressant treatment.

After those 12 weeks, 55% of patients who never took an NSAID during the study period got better and were no longer depressed. That compared to 45% of participants who said they took an NSAID at least once and stop being depressed.

The researchers note that they couldn't separate people who took an NSAID only once or twice during the 12 weeks from those who regularly took NSAIDs, which are used to treat arthritis and are often given to people who have recently had a heart attack.

Warner-Schmidt and her colleagues also didn't find that NSAIDs interfered with other, non-SSRI antidepressants, which include Wellbutrin and Cymbalta.

Dr. Solomon Snyder, a neuroscientist at Johns Hopkins Medical School in Baltimore who will have a commentary coming out with the print study, said in an email that the findings show that "if someone is receiving SSRIs, he/she should avoid NSAIDs."

However, Snyder told Reuters Health, "Such a recommendation may well be controversial and cause difficulties for patients with arthritis and other conditions which benefit from NSAIDs."

The authors said that based on the data they used, it was impossible to prove that NSAIDs stop SSRIs from working. It's possible, for example, that people who have underlying conditions that require drugs such as aspirin and ibuprofen have more trouble recovering from depression.

However, Warner-Schmidt said, "The animal studies suggest there's a direct interaction between these two drugs."

Dr. Michael Thase, a psychiatrist from the University of Pennsylvania School of Medicine who was involved in the original research on humans used by the authors, told Reuters Health that the new analysis is "intriguing," but that his data don't definitively support the animal studies.

However, Thase said, "Given how commonly the NSAIDs are used, this finding certainly needs to be followed up."

Warner-Schmidt added that it wasn't clear how the interaction between NSAIDs and SSRIs might be happening, and that future studies will need look more closely at that question.

Source: http://bit.ly/s1ech Proceedings of the National Academy of Sciences, online April 25, 2011.